Antenna



Feb@ 20 W4@ H. wwwa-.Lm MW Mmmm Filed out. 2,0, 1937 l @@wwwmf/ 'WRNEY Patented Feb'.2o194o y UNITED STATES TENNA Harold A. Wheeler, Great Neck, N. Y., assgnor to Hazeltine Corporation, a corporation of Dela- Ware - Application october zo', 1937, serial No. 169,922

11 claims. `(c1. 25o-s3) signed, in so far as possible, so that the radiated v l energy will be concentrated in a horizontal plane.

However, antennae designed for this purpose generally have undesirable directional characteristics in the horizontal plane, so that their signal field strength varies widelyat receiving stations which are equidistant from the transmitter, but

in different directions.

It is an object oi the invention to provide an antenna for the radiation or reception oi horizontally polarized waves which are concentrated in a horizontal plane, but which are nondirective in that plane. p

In accordance with the invention, an antenna comprises a loop in a horizontal plane having, preferably.' the approximate connguration of a 3J lemniscateV or iigurem. A vertical array of such loops having their longitudinal axes an gularly displaced around the vertical is preferable. In a preferred embodiment, the loops are vertically spaced by a distance approximately equal to onehalf the wave length 'of the signal frequency and the cross-over point of each. loop in the array is connected to a vertical transmission line so that consecutive loops arev at consecutive voltage maxima on the transmission line,

4o that is,points which have maximum voltage of opposite polarity.

For a better understanding of the invention,

together with other and further objects thereof,

reference is had to the following description taken in connection with the accompanying drawing, and itsrscope will be pointed out in the appended claims. Fig. 1 of the drawing is a perspectivev viewof a-portion of an antenna conf structed in accordance with the invention, while F152 is a perspective view of a further modification of the antenna o! theinvention.

Y 1 of the drawing comprises fa four-wire vertical transmission line havingtwo pairs of conductors IB, II and I2. 'I3 disposed at ithe II edges of a square prism. Horizontal loops Il and I5, each having the approximate configuration of a lemniscate or figure 8, are connected to the transmission line, preferably at points thereon having a vertical displacement equal to one-half .the wave length of the signal to be transmitted or received. A. signal-translating device it, forming .no part ofthe present invention, which may comprise a translating circuit of a transmitter or receiver, is shown in dotted lines connected to the transmission line it, ii and it, it. The length' m of the Wire contained in each half of each loop `is also preferably equal to `one-half the wave length of the signal.l As the capacitive eect of a horizontal loop transmitting antennafalters its directive` characteristics, both with regard to the M amplitude of a radiated wave and with regard to its plane of polarization, it is desirable that such effect be as small as possible. The capacitance effect in a loop antenna may be minimized by applying to the terminals of the loop a voltage 2d balanced with respect to ground. lThe center point of the loop is then at ground potential. In the case of a double loop, that is. a loophav-l ing the approximate configuration of a lemnis cate or figure B, the two ends operate effectively gp in parallel in the horizontal plane and have additive magnetic effects, but opposing capacitive effects. If consecutive vertically spaced loops are angularly displaced around the transmission line, further compensating capacitance eiects are obad tained, thus further tending to produce a substantially nondirectional characteristic in` a horizontal plane. It will be seen that the antenna shown in the drawing meets these requirements. Thus, wiresi and II, comprising one 35 side of the. transmission line, feed one side of. eachk of the loops` I4 and I5, while wires I 2 and I3, comprising the other side of the transmission line, feed the other side of each of the loops. A. voltage balanced with respect to ground is im- .30 pressed between the conductors I0, II and I2, It in the case of a transmitter, or is developed therebetween in the case of a receiver. The two pairs of feed wires providegeometrical symmetry and Adouble loops, it will be understood that any numu ber of loops can be used to effect the desired concentration of radiation inthe horizontal plane andan antenna having four or eight double loops is suggested, an even number being preferred.

Inconsidering the operation of the antenna described above, it will be noted that opposite halves of eachv of the double loopsv carry currents which are in the same direction around the loops, for example, counterclockwise, and thus have additive electromagnetic and electrostatic radiation effects in the horizontal plane. Adjacent vertically spaced loops have terminals oppositely connected to the wires of the transmission line, but as the loops are spaced a half-wave length, the voltage applied to the loops is also reversed so that the magnetic effect of the loops addin a horizontal plane. A

While the invention has been described with respect to an array'of horizontal'loops having the approximate configuration of a lemniscate or figure 8, it will be understood that applicant does not wish to limit his invention to an array of loops having this particular shape, but that the invention is equally' applicable to any array of horizontally disposed loops.

Furthermore', while a four-wire vertical feed line has been shown as preferable, some of the advantages of the invention may be obtained by using a two-wire line or a single vertical wire with the vertically consecutivey loopsdisposed at voltage maxima of opposite polarity, so that the required direction of current flow in each half of the loops is obtained. An antenna structure comprising a single vertical feed .wire is shown in Fig. 2 of the drawing. The antenna of Fig. 2 is generally similar to that of Fig. 1 and similar elements have been given identical reference numerals. The antenna of Fig. 2 comprises horizontal loops il and l5 disposed at voltage maxima of opposite polarity along the vertical feed wire i8'. In considering the operation of the antenna of Fig. 2, it will be seenv that the principle involved is the so-called voltage feed principle, which is commonly employed in feeding simple aerials, such asdoublets, either singly or in complicated arrays, 'Ihis principle is applicable to the antenna of Fig.'2 because each loop is merely two half doublets or one Whole-wave doublet bent around to form a figure 8. The voltage feed principle is based on feeding the antenna at. a point of maximum impedance.- The impedance is Yso high that the current iiowing into the antenna is -very small. 'I'he current is so small that it returns to ground through the capacitance in open space. Each loophas maximum impedance between its terminals which may be considered as the adjacent` cross-over points, at the operatingv frequency. Each loop is connected at a voltage maximum point along the transmission line. At such maximum voltages, very little current iiows in each loop in order to supply its power. y

While there has been described what is at ypresent'. considered to be the preferred 'embodiment of the invention, it will be apparent to those skilled in the art that various changes and modiflcations may be made therein without departing' from the invention, and it is, therefore, aimed in A the appended claims tocover all-such changes andv modifications as fall within the true spirit point, the loops of saidgure 8 being effectively connected in parallel with respect to said terminals.

2. A signal-translating antenna comprising conductors having the approximate configuration of a figure 8 disposed in a horizontal plane, whereby said conductors are symmetrically disposed with' respect to ground, said antenna having terminals on said conductors adjacent their cross-over point.

3. In combination, a signal-translating an@ the approximate configuration of a gure 8, and Y a balanced transmission line having conductors connected, respectively, to the conductors of said antenna adjacent their cross-over point, the loops lof said figure 8 being eiectively connected in parallel wtih respect to said terminals.

`5. In combination, an array of vertically spaced antennae each comprising conductors having the approximate shape of a figure 8, and a single-Wire transmission line, each of said antennae having one conductor thereof connected at the cross-over point to said transmission line at one of the voltage maxima of said line.

6. In combination, an array of verticallyspaced antennae each 1 comprising conductors havingthe approximate shape of a figure 8, and a single-wire transmission line, each of said antennae having one conductor thereof connected at the cross-over point to said transmission line at one of the voltage maxima, the individual loops -having the approximate shape of a igure 8, and

a balanced transmission linehaving conductors connected respectively to the conductors of each of said antennae adjacent the cross-over point, said antennae being spaced along said transmission hne a distance approximately equal to onehalf wave length of the operating signal and having axes of symmetry angularlydisplaced about said line.

9. In combination, an array of antennae each comprising conductors having theapproximate shape of a gure 8, and a'balanced transmission:

line having conductors connected respectvely to the conductors of each of s aid antennae adiacent the cross-over point, said individual Jantennae being spaced along said transmission lineandere i 3 11. In combination, an array oi antennae each comprising conductors having 'the approximate shape oi a gure 8, and a balanced four-wire transmission line having conductors symmetrically connected respectively'` to the conductors 'of each oi said antennae adjacent the cross-over point, said individual antennae being spaced along said transmission line.

HAROLD A. 

